 Transport Neutral Encapsulation Format

Transport Neutral Encapsulation Format (TNEF) is a proprietary email encoding format developed by Microsoft to encapsulate various data types and structures in a way that can be transmitted over email. TNEF is primarily used in Microsoft Outlook and Microsoft Exchange environments. When an email is sent using TNEF, it packages the email content along with additional information, such as attachments, meeting requests, and rich text formatting, into a single message body.